I'm using LibreELEC 7.90.008 on Wetek Hub.
EDIT: The original post was inaccurate as the capture software was lying to me. I updated the post.
Basically, the problem boils down to the fact that LibreELEC (or probably just Kodi, but I have no other platform to test) doesn't honor the VUI flags that include the colormatrix tags (Rec. ITU-T H.264 Annex E) and instead relies on resolution alone to detect if BT601 or BT709 should be used. This fails for standard resolution video that was produced in HD and was meant to have the YUV-RGB conversion done with BT709 coefficients, despite the correct flags present in the h264 video stream...
e.g: correct on the right-hand side, LibreELEC on the left-hand side
I don't know if there is much interest in fixing that, I should probably bug the upstream directly.
Note that if I disable hardware acceleration, it seems to work correctly: